[ARC5] Zero Beat Question

[Richard Knoppow]

     I have posted quite a bit on zero beating so this may be too much.
     I learned the "three oscillator method" from a General Radio 
instruction book for a heterodyne frequency meter which was part of a 
frequency standard.  The idea was to beat the unknown signal with a 
known marker and use a BFO such as that in a communication receiver or a 
regenerative detector set to just oscillate to give an audio beat that 
would wax and wane as the unknown beat against the signal from the 
interpolation oscillator.  It is possible to match two frequencies to 
within a few Hz per _minute_ if a meter is used to watch the relative 
strength of the beat. This can be used to set the calibration oscillator 
in a communications receiver to WWV or some other high accuracy 
standard. The idea suggested by someone (should look it up) of using 
background noise is essentially the same thing, the noise taking the 
place of the third oscillator although it may be harder to hear. I just 
tried this on a Collins 51J-3 and it works very well.
     There are probably other tricks.

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL